What Is Diatomaceous Earth? What to Know About This Pest Control Powder

Of all the trendy DIY pest control methods out there, there's no question that diatomaceous earth is the oldest one—we're talking tens of millions of years old. But what is diatomaceous earth used for, and why is it often touted as the cure-all pest control? 

Before sprinkling this ancient dust around your kitchen, garden, and front porch, let's review diatomaceous earth safety tips, how it works, and when it's your best option for fighting unwanted bugs.

What Is Diatomaceous Earth?

According to the National Pesticide Information Center (NPIC), diatomaceous earth—aka DE or diatomite—is a powder or concentrated liquid made up of fossilized aquatic organisms. Known as diatoms, the organism's skeletons are made up of the versatile material silica, which can be mined from the bottom of major bodies of water. 

In other words, DE is made from very, very old fossils ground up into dust that have several uses around the home. And while DE does come with some safety precautions—more on this below—you'll find food-grade diatomaceous earth in everything from pesticides to toothpaste. 

The small fossils act as a natural abrasive for teeth, an additive to enhance the pigment of paint, and of course, a deterrent for pests.

How Does Diatomaceous Earth Work as a Pesticide? 

Unlike poisons and bait traps, you don't have to rely on pests to consume DE for it to work. The small sharp fossils scratch and wear down the exoskeleton and soft skin of insects as they pass over the dust. 

The dry dust also absorbs the oils on the bug. Between the breaks in the skin and the oil absorption, the insects eventually dry up and die. Larger insects may also choose to consume the diatomaceous earth powder, speeding up the process.

Is Diatomaceous Earth Safe to Use as Pest Control?

While diatomaceous earth is not considered poisonous, the (CDC) note that it can cause skin, eye, and respiratory irritation if you inhale it. Professionals who handle large amounts of silica products like DE must be aware of the potential risks of long-term exposure. 

At home, however, diatomaceous earth is safe to use when you lower exposure to your skin, eyes, and lungs with proper personal protective equipment such as gloves, goggles, and a face mask. 

Follow the diatomaceous earth safety tips below, and read the manufacturer’s instructions before application too. If you have an active infestation or concerns about using pesticides around pets or children, hire an exterminator in your area to help. 

Choosing the Right Grade

You will find two grades of diatomaceous earth when shopping for pest control: pool grade and food grade. Pool grades also go by garden grade and filter grade on some bottles. The variety goes through several additional processes that transform some of the silicon dioxide into crystalline silica. 

The warns against the effects of exposure to crystalline silica, including a severe lung disease known as silicosis. For this reason, never use pool-grade DE for anything other than directed, such as in pool filters. Stick to food-grade diatomaceous earth for pesticide treatments. 

Safety Around Children

While there are no safety warnings specifically for children, according to the NPIC, it's best to only treat lightly trafficked areas with DE to lower the threat of skin, eye, or respiratory irritation in all members of your home, including kids. When spreading DE on carpets, treat the area and vacuum up excess when the children are not home.

Safety Around Pets

There are no known major threats to cats, dogs, and other pets when using diatomaceous earth around the house. Similar to adults and children, DE can cause slight eye, skin, and lung irritation with frequent exposure, so it's best to treat it when your dog is out for a walk and in areas where they won't track it all over the house. 

Another option is to close off rooms for 24 to 72 hours that have been treated with DE pesticide powder, vacuum thoroughly, and then reopen.

What Pests Does Diatomaceous Earth Kill? 

Now that you know what diatomaceous earth is and how it works as a pesticide, let’s talk pests. The smaller the pest, the more likely diatomaceous earth will make an immediate impact. Some homeowners swear by the method for larger insects like cockroaches in your home as well, though it may take more time to break down their exoskeleton and control an infestation. 

However, homes and gardens overridden by small insects and spiders can simply spread the natural product without harming home surfaces or plants.

Use food-grade diatomaceous earth powder to kill the following pests: 

• Fleas

• Mites

• Slugs

• Worms

• Bed bugs

• Ants

• Silverfish

• Beetles

• Snails

• Aphids

• Ticks

• Gnats

How to Apply Diatomaceous Earth for Pest Control

Diatomaceous earth can be applied both inside and outside to treat common garden pests. However, always read the safety instructions before proceeding and wear goggles, gloves, and a face mask. 

If you have a more persistent infestation, hire a pest control specialist to get ahead of the problem. Diatomaceous earth can play a role in deterring pests, but is not always a strong enough method for controlling major issues.

Treat Trouble Areas

When treating trouble spots indoors where you've seen cockroaches, ants, or beetles, leave a small pile or light dusting of DE for several days. You can line the baseboard of a room, the area along the inside of a window, or underneath furniture where you know the insect hides. Your bottle of DE will often include specific application tips to avoid sending too much dust into the air.

Focus on Carpets

For mites, fleas, or bed bugs in your home, apply a thin layer of DE to the outside of your carpets and rugs in lightly trafficked areas. You can also dust your carpet with DE, let it sink into the fibers for a day without disruption, and then vacuum up the dust and dead pests along with it.

Spray Your Garden

You can also purchase a concentrated liquified version of diatomaceous earth or create a solution yourself. Mix 2 to 4 tablespoons of DE with 1 gallon of water and spray the solution on infested plants in the morning or late afternoon. Once the solution dries in the sun, the particles will deter garden pests like aphids and slugs.